| Abstract Scope |
Zirconium carbide is an ultra-high temperature ceramic with applications in nuclear and aerospace industries thanks to its maximum melting temperature around 3700K and high hardness at elevated temperatures. Zirconium carbide is a candidate for tuneable ceramics, as it has a wide range of stoichiometry, facilitated by carbon vacancies, with varying properties. However, carbon vacancies exhibit strong ordering that can persist to some degree at high temperatures. Furthermore, the ordering is affected by the presence of impurities e.g. oxygen. Fabrication requires cooling from higher temperature disordered states, resulting in trapping of metastable phases and complex partial ordering. The vacancy ordering significantly affects the thermodynamic and mechanical properties, and so fabricating zirconium carbide with specific properties can be a significant challenge. This work uses first-principles calculations to examine the properties as a function of temperature, composition, and degree of ordering, and combines theoretical and experimental data in a single, consistent CALPHAD model. |